(1) Field of the Invention
This invention relates in general to data recording and, more particularly, to a technique for preventing the loss of data from or during a recording operation.
(2) Description Relative to the Prior Art (Problem)
Technologies which are associated with information recording have made spectacular progress toward tapping the information bearing potential of magnetic surfaces. A roadblock to achieving very short wavelength recording, however, is the occurrence of signal losses associated with small imperfections in such surfaces. When a magnetic surface is used at a conservative recording density, a surface defect seldom results in a loss worse than a burst error of a few bits of digital information. Error correcting codes have been devised to accommodate the occurrence of burst errors. Such codes reconstruct data integrity by using redundant information systematically incorporated into the recording format. The complexity and cost of these methods, however, is exponentially dependent upon the length of the burst errors that they are required to handle. At the present state-of-the-art, the use of large scale integration has made practical the implementation of burst error correcting codes which can correct up to 12 bits of burst errors.
When one records with a very short gap head (a la U.S. Pat. No. 4,302,790) to take advantage of the very short wavelength capability of a high coercivity isotropic magnetic surface, the gain in recording density is so dramatic that the same surface defect--which in the prior art corresponded to, say, a burst error of 12 bits--can now result in a burst error of several hundred bits. Clearly, the recovery from such burst errors is no longer within the realm of practical error correcting codes.